66 yr old diabetic (controlled, no meds): took 10mg for 6 days w/evening meal. Day 4: developed rapid heart beat, chest pain, numbness in fingers, leg pain & ringing in ears. Internist sent me for echo stress test. Day 5: same symptoms but worse; felt like I was SHUTTING DOWN. Internist sent me for holter 24-hr heart monitor. Day 6: saw info about effects like mine, also felt better each day in the afternoon & both incidents were around the same time each morning. I discontinued use and only had numbness the next morning. Be aware of possible severe side effects, especially diabetics.